Sunday, July 26, 2009

The idea that was discussed was the fine-tuning in the universe, sometimes called the “anthropic principle”. The idea is that the universal constants in the universe (such as the universal gravitational constant, strong/weak nuclear force, speed of light, etc.) seem to be “finely-tuned” to allow for sustaining life. For example, if the electromagnetic force constant was different by 1/10^40 (0.000000000000000000000000000000000000001%), then we wouldn’t have any molecules, just elemental atoms floating around.. and obviously you can’t get life without molecule formation.
This fine-tuning in the universe is something that leading atheists like Richard Dawkins acknowledges as perhaps the “biggest challenge” to atheism. Below is the video where Richard Dawkins talks about this. You can post your questions or comments on the anthropic principle. Dawkins does give his reply (which he fleshes out in his book "God Delusion") to the mystery of the anthropic principle, so you can comment on that as well.

49 comments:

Their argument for why they don't believe the fine tuning of the universe is the result of design is pretty thin. They basically say it should have been designed better. Listen toward the end and one of them (not Dawkins) says something to the effect of, "Why are there so many extra planets?" as one example. I guess in a "perfect" solar system (in this guy's mind) you'd only need one with life on it. Who is the judge of good design? Fallible man?

I was at the Academy of Science the other day and watched the planetarium show that they have there, and one thing that was noted is that the gas giants in the outer solar system, Jupiter in particular, are vital to the survival of life on earth because their gravity pulls in most of the deadly asteroids and comets that could potentially collide with earth. If you ask me, the fact that we have planets out there that take the brunt of the cosmic assault is further evidence of design.

An argument that is commonly used to show that the Anthropic Principle cannot be used to say that naturalism is unlikely:

Let's assume that premise A = naturalism is true. Premise B = the universe is "life-friendly", i.e. it has finely tuned laws that allow life.

The Anthropic Principle says: if the probability of B being true (given A) is very small, then the probability of A being true (given B) is also very small. In other words, if the probability of the existence of a finely tuned universe is very small (given naturalism), then the probability of naturalism being true (given the observed fact that our universe is finely tuned) is also very small.

However, P(A|B) (the probability of A, given B) and P(B|A) (the probability of B, given A) are not equivalent.

Let's take a game of poker as an example.

A = You have a Royal Flush.B = You win the game.

P(A|B), the probability that you have a Royal Flush given that you won the game, is almost 0. You can win the game with many different hands, not just a Royal Flush (which is extremely rare). However, P(B|A), the probability that you win the game given that you have a Royal Flush, is almost 100%. Thus, the two are not the same, but rather are opposites.

As many atheists argue, the Anthropic Principle cannot be used to say that naturalism is unlikely based on the tenets of probability theory.

This is a good objection. We actually talked about this in class (remember the sleeping beauty analogy)... so I'll hold off and let the students of apologetics MYT try their hand at trying to answer this objection.

It seems to me that we cannot draw the comparison between the two logic relationships Royal Flush/Winning the game and Naturalism/Fine-tuning. The contingency between Royal Flush and Winning the game is only if we're talking about P(B|A). On the contrary, the relationship between Naturalism and Fine-tuning is contingent either way P(A|B) and P(B|A). This is not an exhaustive argument, but I think it's a misleading comparison.

To expand on the objection a bit more... Let's use the Royal Flush analogy:

Imagine that in order for someone to be alive, she needs to draw 5cards from the deck randomly and get a Royal Flush. Well, the atheistic argument goes like this: If you find yourself alive, you should not be surprised that you drew a Royal Flush, because that is a 100% certainty, given that you are alive. Otherwise, you would not be there to wonder about it. Applied to the fine-tuning argument, it goes like this: Given that we are here, we would, of course, find the conditions necessary for us to be here.

Billy, is this a fair analogy of the probabalistic argument against the fine-tuning issue?

Yep, the argument that "Given that we are here, we would, of course, find the conditions necessary for us to be here" is a classic example of a tautology, which is what I think you're getting at. Which would be effective, if you can get your atheist friend to agree that your analogy parallels their analogy. Though I think you would get into an argument over the specifics of your analogies...which is why I don't prefer inductive arguments in the first place.

I think a deductive argument would be better, using the same principle of Bayesian probability. Let A = the proposition that God exists, and B = the proposition that the universe is life-friendly. The fine-tuning argument would say: learning that B would increase the probability of A, that is, P(A|B)>P(A). This inequality holds because P(B|A)>P(B): learning that God exists increases the probability that the universe is life-friendly and (per Baye's Theorem):

P(A|B)/P(A) = P(B|A)/P(B)

Thus, with B as a given (we know that the universe exists), we can reasonably deduct that the probability of God existing increases.

In any case, the whole criticism-by-probability argument doesn't do a whole lot, except to thoroughly confuse everyone involved. Saying that "you can't use the Anthropic Principle to say that naturalism is unlikely" is a purely defensive argument, which merely forces the atheist to form more defensive arguments in the vein of (you can't use that argument because...) to answer all the theist offensive arguments.

Richard Swinburne had a analogy to reply to this issue.. He said to imagine that you were kidnapped by an evil kidnapper, and he ties you down on a chair, and there are 50 machines hooked up to 50 guns pointing at you. These 50 machines choose one card at random, and if it chooses anything else other than ace of spades, the gun will fire and you'll be killed. And the kidnapper leaves the room, and then one by one, the machines draw a card, and each of the 50 machines amazingly draw ace of spades! And while you're sitting there stunned, the kidnapper comes in and tells you that you shouldn't be amazed, because the fact that you're alive means that all 50 machines chose the right card.. or else you wouldn't be here to wonder about it! Swinburne then goes on to say that of course the victim is right to be amazed and even suspect that there was some kind of rigging of the deck! The kidnapper is the one who needs to explain how this astronomically unlikely thing has happened, rather than just dismiss it and brush it off as a given. I know that analogies often fall short, but I think this analogy by Swinburne is hard to criticize, because he is putting the burden of proof on the atheist who is making the strange claim that this amazing fine-tuning is actually to be expected. Is there something that we could pick at in Swinburne's analogy?

Well, I actually think the atheistic argument is more than a tautology... it's more like the "selection bias" argument. If we've had a billion trillion trillion kidnappers, and a billion trillion trillion people sitting in chairs, then perhaps you actually SHOULDN'T be surprised that you are alive (you just happened to be the lucky one!) The issue is how many chances (draws) we got. That seems to be the real issue when it comes to the fine-tuning argument. That's why oscillation theory (that we've had infinite number of Big Bangs) and multiverse theory (that we have infinite number of universes) seem to be what people are moving toward in order to explain the fine-tuning in our universe. The motivation seems plain -- if you've had infinite tries, then we shouldn't be surprised to find ourselves in a universe that "worked". But that's a theory that not even Richard Dawkins is willing to go for.. because there are some major problems with them.

Wouldn't it seem, though, that the fact that there is only one planet with life (yet known) be proof for life's rarity and not for a premise that the universe is life-friendly or all that fine-tuned? In fact, there being only one place we know of where life exists would seem to be proof that life is, indeed, extremely rare. Thus, isn't the argument of fine-tuning rather weak because of the billions of billions of stars we only know of one around which orbits a planet which supports life? Therefore, is the universe really that fine-tuned? It would instead appear that with the large number of planets without life that the universe is incredibly hostile to life and rather unsuited to it.

Research done by F.C Adams would seem to postulate that the universe could arise from different values of some of the fundamental constants, and doesn't this weaken the argument that "only" with these constants can the universe be made? What proof can be offered to say that the universe is so fine-tuned that any variation in the constants would not create simply a different universe instead of no universe, which is what is seemingly being argued here?

I haven't heard that analogy before, though it seems similar to Swinburne's firing squad analogy, and both are quite compelling, in an intuitive sense. Of course, an atheist can always come up with some kind of argument, such as using complicated statistics to differentiate between physical and epistemic probability, or even completely-out-of-left-field arguments like multiverse theory.

I say "complete out of left field" because Multiverse theory is pretty ridiculous. First and foremost, there's no evidence for it and there never will be. Finite reality is our universe, and our "evidence" is limited to it. Finding evidence for something outside of our finite reality is impossible. Second, positing multiple universes doesn't get rid of the fact that they were "caused by nothing", and thus need a First Cause. Third, multiverse theory is philosophically untenable. In an infinite number of universes, anything is possible. The theory allows people to say that we need not blame terrorists for 9/11, but that we merely happen to be in the universe where the planes- though they appeared to have been flown by the terrorists- actually hit the towers by accident. Given an infinite number of universes, that situation would be true in at least one of them, so maybe we're living in that universe. The reasoning is ethically despicable.

Oscillatory universe theory is interesting, but doesn't really work. An infinite number of oscillations would be impossible, because of the Second Law of Thermodynamics. A First Cause would still have to be explained, current research suggests that the universe is open, and there are no current string theoretic descriptions of an oscillatory "bounce".

Anybody can come up with any argument to anything. However, I hope that once atheists start moving out of intuitive, common-sense reasoning into the realm of speculation and metaphysics, they realize that they're just arguing for the sake of arguing, or for the sake of preserving a naturalistic and nonmoralistic worldview.

Regarding the previous question from Anonymous:"Wouldn't it seem, though, that the fact that there is only one planet with life (yet known) be proof for life's rarity and not for a premise that the universe is life-friendly or all that fine-tuned?"

Good question. It is true that life seems very very rare, perhaps unique. Given all the things that need to go "right" in order for a planet to be able to sustain a viable ecosystem, it's likely that we might be truly alone in this entire universe. (Even given the immensity of the numbers of stars and possible solar systems).

If that is the case, then, it does seem to show that the universe is actually quite hostile to life, and I think you're right in saying that (except Earth being a very rare exception). However, when we take a look at the actual arguments of the anthropic principle, the argument is precisely that if these constants were to be changed even a little bit, it would have been IMPOSSIBLE for any life to be birthed in such a universe. You might still have a universe, but not something that can possibly have life.

For example, you change the electromagnetic force constant by an incredibly small fraction (1/10^40), you would end up with a universe with just atoms, no molecules. Well, that's pretty bad. A universe would exist, but in that universe, there's just no way you could possibly have any organisms. You increase the strong nuclear force by 2%, and you get no molecules. You decrease it by 0.3%, and you get no suns, not good for life, since suns are the things that produce elements that are heavier than helium. You change the speed of expansion of the universe by 1/10^55, and you either have the universe collapse upon itself long long ago, or you get a universe without galaxies, without solar systems, without planets.. That's not good for life. If you change the ratio between electrons and protons in the universe by 1/10^37, then you have a charged universe, in which gravity (the weakest force out of the 4 fundamental forces) does not have a chance to take over. That means no suns, no planets, no galaxies. Not good for life. And this list can go on and on. Regarding your question about the vastness of the universe and the rarity of Earth, there's even a reason for that, which I can't really go into now. But suffice it to say that when we say that the universe is fine-tuned for life, we're not saying that therefore the universe is teeming with life. It is fine-tuned in the sense that the universal constants seem to be carefully aligned to have galaxies, planets, suns, heavier elements (such as carbon), molecules, etc. So in a sense, you are right in saying that changing these constants only result in a different universe. However, as Stephen Hawking writes in his "A Brief History of Time" -

“The remarkable fact is that the values of these numbers seem to have been very finely adjusted to make possible the development of life… Most sets of values would give rise to universes that, although they might be very beautiful, would contain no one able to wonder at that beauty.”- Stephen Hawking

By the way, if you want more information about why Planet Earth, even when the universe is fine-tuned for life, might be the only one, there're actually very good reasons for believing that.

You can find it in:"The Privileged Planet" by Guillermo Gonzalez and Jay Richards

"Rare Earth: Why Complex Life is Uncommon in the Universe" by Peter D. Ward

Like I said above, fine-tuning in the universe is there to simply create suns and planets and galaxies.. Just to create those basic entities, we already have an astronomically improbable situation. The rarity of the earth actually serves as yet ANOTHER layer of fine-tuning (well, in the case of earth, it's not really fine-tuning in the sense of the universal constants.. People can just say that we're astronomically lucky. The chances of having a life-sustaining planet, it turns out, is far less than the total number of possible planets in the universe)

Right, I did a term paper on the Rare Earth hypothesis for an astronomy class, and if anything, it's loads more evidence for the fine-tuning of the universe. You could even treat it as a fine-tuning-of-the-Earth argument.

And in reply to F.C. Adams, the fine-tuning argument isn't that a universe can only be made if these constants are the way they are, the argument is that a universe suitable for life can only be made if these constants are the way they are. I did some more research on F.C. Adams, and the only thing I could find about him was a research paper in which he postulates that stars could form in universes with different physical constants. Among the groups of physical constants that he came up with, stars would be able to form in 25% of them. The formation of stars is just one of the many variables involved in the fine-tuning of the universe, and saying that they could form in 25% of a group of universes with arbitrarily derived physical constants is a pretty weak argument.

Furthermore, a significant portion of the "stars" that F.C. Adams postulates are black holes and dark matter bodies that take the role of stars. Black holes can theoretically accomodate planets if they are an ideal size (within a tiny range). However, black holes also undergo Hawking evaporation, where massive amounts of gamma radiation are emitted by the black hole, which would make black holes terrible "stars" for life-sustaining planet formation. Dark matter "stars" are entirely theoretical, since the presence of dark matter can only be inferred from gravitational effects on galaxies and galaxy clusters. Also, the majority of the dark matter in the universe is postulated to be made of neutrinos, not atoms. And it'll be pretty hard for life to evolve without atoms.

Thanks, Billy, for that, although I already knew that but chose not to present that information.

Daniel, thanks for your post. That's a good counter-argument to the point I presented. I think it must be admitted, though, that we can't really say that another universe with life couldn't be possible with slightly different constants; however, it's correct to say that the probability of such an occurrence does seem to approach zero and may not even be worth considering except by those who get paid to do so. I had most often heard "fined-tuned" be incorrectly applied to the idea that since there is ONE planet with life, then the universe is obviously suited to life- this is a ridiculous statement. It seems it'd be much more correct to say that in spite of the hostility of the universe, we're on a planet that can support life and that that improbability should be examined.

Yes, it's true that another life-supporting universe could be possible with slightly different constants. To be more precise, I think what you mean is "slightly different constant sets" - because of course, the very definition of fine-tuning argument suggests that there's a "range" of possibilities that would still work... but it's an extremely narrow margin of error. So what you mean is that even if the universal Gravitational constant is way out of range, if we also tweak the other constants (like the speed of the expansion of the universe, the electromagnetic force constant, speed of light, strong/weak nuclear force, etc..), then we could have a universe with a very different periodic table, which could still sustain life made out of other elements that are not found in our universe.. is that right? (because in our universe, it seems like only carbon can make complex life - not simply because we only see carbon life, but because of the fundamental properties of carbon that are unique).

When I gave this talk with our ISM department, someone actually brought this up as a question, and the answer to that question is kind of complicated -- the question is really suggesting that the solution space (mathematically speaking) is a continuam.. (e.g., even if gravity goes out of bounds, there could be a solution if other constants can change out of bounds in the exact same way).

In a way, that's true. A more exhaustive discussion on the fine-tuning argument would have covered this. What is found is that the fine-tuning of the constants is not just on the individual constants, but even the RATIO between the constants and forces must be extremeley fine-tuned. For example, you can't have strong nuclear force go too high and the weak nuclear force go too low... if that were to happen, there's no solution possible, no matter how much the other forces get tweaked. So the solution space (because of the ratios that need to be maintained across all these constants) seem to be extremeley narrow, because the fine-tuned ratios between the constants must be maintained. Given that we're talking about something like a 50-dimensional solution space, this narrow line of possible constants would pretty much constitute an astronomically unlikely event to have come about by chance. So you are right, there is a possible universe that's built out of some other matter that does not exist in our universe.. But the ratio of all the constants in that universe would also have to be extremely fine-tuned to make complex molecular structure possible. And given that there are infinitely more possible universes that do not have this correct ratio, you might have probablistically gained an infinitesimal advantage in chance, but that's not much further from zero.

I read the many comments about fine tuning of the universe and the possible existence of God.

I'm not as smart as you folks are but here is what settles the argument for me:the existence of good and evil.These can't be the result of random chemical changes over time because these qualities are not chemical in nature but spiritual. How can evolution use good and evil to achieve what seems to be the best possible result. If it could do that then natural selection is intelligent and therefore all we see in life is the work of that intelligence,in other word a creator.I reject that. God is God, not natural selection. He is a person not a process.

If you didn't have explosions in space like supernovae and creation of new stars, then you wouldn't get any space junk flying through space.

If you didn't have a need for stars, then you wouldn't need explosions.

If we didn't have life, then we don't need stars.

So the problem is that we need to have carbon-based life, and that means we need to have creation of stars as well as non-gaseous planets, which makes a lot of "junk" flying through space... and so we better have some protection. It's not bad design to create protection against necessary by-products.

In other words, the existence of asteroids seems to be a necessary by-product of a universe that has explosions, which are necessary for creation of stars.

I don't think we can characterize asteroids as something that are "made" for the specific purpose of destroying planets.

When we design an engine, one of the by-products of the engine is that there are these combustion explosions and thus heat is produced. So we design a cooling system to protect other parts of the engine from the heat. That, I don't think, is bad design.

Our existence is very very unlikely and tenuous and fragile, but that's an argument against the universe being "fine-tuned" for life. That's why humans have spent thousands of years fine-tuning our environment ourselves.

The fact that we're possible, and we exist, however unlikely isn't an argument for divine intervention. True, the universe could not look the way it does without the same fundamental particles, constants, and laws, but we're talking about God here.

There's no reason that I can see, that God couldn't come up with a completely different kind of universe featuring completely different bodied people, in a way that did not have the level of carbon-based suffering that this world has.

If God went to all this effort to fine-tune the universe for life and guide evolution up to us, specifically, you have to explain why God inflicted all this suffering as an inherent chemical part of the experience of carbon-based life.

Because there's a lot of illness and suffering that is a direct result of the way we came to exist, eg, genetic illness; illness related to the inherent variability of carbon-based molecular structure that was praised in the lecture last night.

If fallible man is capable of judging that we're fine tuned she's capable of judging that we're not fine tuned.

Billy: " Yep, the argument that "Given that we are here, we would, of course, find the conditions necessary for us to be here" is a classic example of a tautology, "

No, a tautology would be, "Given that we are here, we exist." The atheist argument is actually, Given that we are here, we CAN be here. That is not a tautology, but a logical induction. From this the atheists conclude, therefore we might not have existed. Christians conclude, therefore we must have existed.

"Given an infinite number of universes, that situation would be true in at least one of them, so maybe we're living in that universe."

This might be true - but the great thing about evidence and reason is, you can actually find evidence to figure out which universe you're living in.

Then there is inertia. If all the universes started out at the same "time" then there's basically no way they'd be remotely similar down to events like 9/11. That anything is possible doesn't mean that therefore everything must exist.

Multiple universes would diverge from each other rapidly. There are also infinite planets in this infinite universe, but that doesn't mean there's another planet in the universe that's evolved exactly as we have for 5 billion years EXCEPT 9/11 was an aviation accident. Everything about our world is both unlikely and inevitable. That's the beauty of chaos. There are 6 billion people on this planet but no two of them are alike and none of them are replicable or were predictable.

You bring up a lot of issues in succession (including the problem of pain and suffering), but I think for the sake of coherent discussion, we should try to limit our discussion to the fine-tuning argument. Hope that's okay. There are other resources and threads that talk about the problem of evil, which is actually quite different from the fine-tuning argument.

Let's talk about the issues that you brought up.

"The atheist argument is actually, Given that we are here, we CAN be here. That is not a tautology, but a logical induction. From this the atheists conclude, therefore we might not have existed. Christians conclude, therefore we must have existed."

I don't think that's what the theists are saying. The theists are actually in agreement with the atheists in that therefore we might not have existed.. But when we look at the constants (and non-constant accidental facts of the universe, like the speed of expansion during the first 1 second of the Big Bang) of the universe, it just seems eerie that all these constants line up in such a way as to produce a viable universe at all. So a theist asks, what might be the reason for this? Theists are not saying that therefore we must exist. In fact, it's one of the tenets of Christianity -- that God did not NEED to create anything.

"Then there is inertia. If all the universes started out at the same "time" then there's basically no way they'd be remotely similar down to events like 9/11. That anything is possible doesn't mean that therefore everything must exist."

Well, the thing about multiverse theory, though, is that you must conclude that the universe-producing machine must still be creating universes constantly to this day and infinitely beyond. So it's not like the multiverse just had one starting point.. that would be, according to the multiverse theorists, being egocentric -- thinking that our universe's beginning point must be the beginning point of all universes. The reason for this "infinity" of universes is that whatever started our big bang, if it's not God, is basically some kind of a principle.. some kind of principle that stands outside of time and space and therefore existed forever. And therefore this "principle" must have been creating universes throughout all eternity.. Therefore we have an infinite number of universes, because universes are being created even to this very moment. Some multiverse theorists would say that every single quantum event (including a random decision you make) creates a brand new baby-universe, branching off from that point.

Given that there are literally infinite number of universes, we must conclude that there are an infinite number of universes exactly like ours, along with universes that are slightly different from ours and very different from ours. Remember, even if the chances are really small, when multiplied against infinity, the answer is infinity. If there is actual infinity (meaning that it's not merely a very very large number), then anything is possible, as long as it's logically possible. Therefore, while it's true that multiple universes would diverge from each other rapidly, when we have infinite universes, they do diverge, but there are also infinite number of universes that fill the gap in between.

"There are also infinite planets in this infinite universe, but that doesn't mean there's another planet in the universe that's evolved exactly as we have"

Our universe is not infinite.. There's a size and mass to it. And we don't have infinite number of planets. We have about 10^22 stars, and far fewer planets. Just wanted to clear that up.. Because if we actually DID have infinite number of planets, then you would HAVE to conclude that there will be planets that are exactly like ours (that's how actual infinity works, as we talked about above).

"Our existence is very very unlikely and tenuous and fragile, but that's an argument against the universe being "fine-tuned" for life."We actually covered this topic in the discussion above in this thread. You can take a look at this.

These are great questions and issues that you bring up, Sierra. The extra issue of problem of evil is a difficult issue, and it's something that we can discuss. (BTW, the problem of evil and suffering is partially covered in our Course 101.)

Hope what I said made some sense. You are of course welcome to ask more questions and provide further comments. And if I misunderstood anything that you've said, please correct me.

BTW, just in case it wasn't clear to other readers of this post, I personally believe that there is just one universe. :) I was just going along with the multiverse theory to show its strange conclusions.

Suffering isn't the same as the problem of evil. It's not a result of evil to get sick or to have a disability. If the malleability of carbon is evidence of god's intervention/design, its downsides have to be included in that.

"Well, the thing about multiverse theory, though, is that you must conclude that the universe-producing machine must still be creating universes constantly to this day and infinitely beyond.

I don't think that's necessary, but even if it's true, what I said still applies. Those universes would not be carbon copies of this universe. Chaotic systems evolve in unpredictable ways.

"And therefore this "principle" must have been creating universes throughout all eternity.. "

You're ascribing agency to something that is not agentic. This is the same problem I have with the term "fine-tuned."

"Given that there are literally infinite number of universes, we must conclude that there are an infinite number of universes exactly like ours,"

Sets can be both infinite and limited. For instance the set of whole numbers is infinite, but none of them are -5 and only one of them has the value "2."

"And we don't have infinite number of planets. We have about 10^22 stars, and far fewer planets. "

That we can see. The unobservable rest of the universe is another story.

"If there is actual infinity (meaning that it's not merely a very very large number), then anything is possible, as long as it's logically possible."

"Suffering isn't the same as the problem of evil. It's not a result of evil to get sick or to have a disability. If the malleability of carbon is evidence of god's intervention/design, its downsides have to be included in that."

Actually, as mentioned above, the fine-tuning argument is on a different category.. it's because fine-tuning argument only gets us to a possibility of a deistic intelligence. It has nothing to say about the goodness/evilness of that deity.. Nor does it say anything about how proficient that design is. For all we know, the deistic being that did the fine-tuning could be some alien outside of our universe or an evil god who wanted to do an experiment. So that's why I didn't want to mix the two topics. Hope that's more clear now.

"I don't think that's necessary, but even if it's true, what I said still applies. Those universes would not be carbon copies of this universe. Chaotic systems evolve in unpredictable ways"

Actually, if you have an actual infinite number of tries, then you do get infinite number of copies. Let's think about this. If we have one other universe besides ours, what are the chances that every single event of that universe (which is a finite number, by the way, since universes had a beginning) is exactly the same as ours? Very very slim, nearly 0... But if you have 2 other universes, that infinitesimal, non-zero chance is doubled, but still so small that it should be considered impossible. But what if you have 4? Well, that chance would quadruple. 10? Billions? How about if we multiply the non-zero possibility with actual infinity? Then you get infinity. Does that make sense?

So when you say, "Sets can be both infinite and limited. For instance the set of whole numbers is infinite, but none of them are -5 and only one of them has the value "2." -- I see what you're getting at.. that might be true in terms of specific numbers, but when we are talking about probability/statisitcs, we are talking about something different. Whatever the chances are, as long as it's greater than 0, if we have to multiply by infinity, you get infinity.

"You're ascribing agency to something that is not agentic. This is the same problem I have with the term "fine-tuned."

Sorry, I didn't mean to ascribe agency to this principle by using the word "create". Maybe I should have used the word "cause". So rephrasing it: "This principle must have been causing Big Bangs throughout all eternity". The point still stands, I think... that this principle, if it's not a free agent, would have been causing Big Bangs throughout all eternity -- therefore, we have an infinite number of universes. (Remember, this principle must be outside of the universe and timeless and eternal.)

"That we can see. The unobservable rest of the universe is another story."Well, I'm assuming that the scientific evidence we have is what we should go with (Big Bang theory assumes a finite universe, by the way.. If the universe started a finite time ago, and it's expanding at a certain rate, then that means it can't be infinite.) Also, there are some major logical problems with saying that there are actually infinite number of suns and planets, but I don't think we should get into that.. (unless you want to?)

BTW, I think a lot of the confusion arises from the difference between actual infinity vs. a large number that's approaching infinity. There's a difference. If I may be so bold as to guess at what your conception of "infinity" is, I think you are thinking of a very very large number that is constantly approaching infinity, but never gets there. That's why you think that the universes (if multiverse is true) can still diverge to a point where there won't be any overlap. Does that make sense? Please let me know which conception of "infinity" you have, because that's where we're sort of missing each other.

"How about if we multiply the non-zero possibility with actual infinity? Then you get infinity. Does that make sense?"

No I don't think so. There are different kinds of infinity. The infinite set of all whole numbers is twice as big as the infinite set of all even whole numbers. The set of all possible universes is larger than the set of all extant universes, even if the total number of extant universes is infinite.

"Well, I'm assuming that the scientific evidence we have is what we should go with"

I'm not going against the scientific evidence. But at the moment we can only see as far as the surface of last scattering. Unless we're actually located at the exact center of the universe, there is a whole lot of universe beyond the horizon of the observable universe.

(Big Bang theory assumes a finite universe, by the way.. If the universe started a finite time ago, and it's expanding at a certain rate, then that means it can't be infinite.)

There's two different senses of the word finite being used here. The universe is spatially infinite in that any two beams of light will eventually diverge. It has not existed infinitely far back in time.

"Also, there are some major logical problems with saying that there are actually infinite number of suns and planets, but I don't think we should get into that.. (unless you want to?)"

My point was more that the universe is much bigger than we can see. 10^22 is the number just in the observable universe.

"No I don't think so. There are different kinds of infinity. The infinite set of all whole numbers is twice as big as the infinite set of all even whole numbers. The set of all possible universes is larger than the set of all extant universes, even if the total number of extant universes is infinite."

That's true. The infinite set of all whole numbers is twice as big as the infinite set of all even whole numbers. However, I have not made a statement about what is more probable or less probable.

I'm just showing you that if you actually have infinite attempts, no matter how impossibly unlikely something might be, you can get it to happen. Do you grant that?

Again, I think the confusion arises because of the misunderstanding of actual vs. potential infinity (explained in my previous comment).

"I'm just showing you that if you actually have infinite attempts, no matter how impossibly unlikely something might be, you can get it to happen. Do you grant that?"

Yes, which is why it doesn't surprise me that in all the universe, somewhere, there'd be at least one planet where life would develop. It's just an odds game and we lucked out. No fine tuning required.

By the way, fine-tuning of the universe is PRIOR to the development of Earth-like planets. (explained above in the comment made on Aug 3, 2009). So the presence of other Earth-like planets (even if there are millions) does not threaten the premise that the universe seems to be configured to produce life-sustaining planets.

The number of planets in the observable universe is finite and unknown. The number of planets in the whole universe is infinite because the universe itself is unbounded and isotropic.

"So the presence of other Earth-like planets (even if there are millions) does not threaten the premise that the universe seems to be configured to produce life-sustaining planets."

But part of your lecture was on how excrutiatingly rare a planet like Earth is. Now you are saying this whole universe was set up to produce Earth-like planets?

It's more plausible and parsimonious that we're a completely unintended side effect of the existence of chemistry. Even if you grant that the universe was somehow set up to produce life, it's a huge jump to say that it's set up to produce human life.

During the talk, I actually made it a point to say that now that we're talking about Planet Earth, we are no longer talking about the universal constants and the fine-tuning in the universe. Rather, I said we're just talking about chance occurrences, depending on how many planets we have in this universe. (there was a slide dedicated to make this distinction clear.. and I said it twice, because I have had people get confused about the two.)

Sorry if that was not clear. For the next time I give this talk, I will try to reiterate this point more.

"Even if you grant that the universe was somehow set up to produce life, it's a huge jump to say that it's set up to produce human life."

I agree. I never made the claim that the universe is set up to produce HUMAN life. I believe I've always said "complex life" or "carbon-based complex life" during the lecture. Wow, I wish I could go all the way to show the universe was made for human life! That would be astonishing Seems like you were giving me more credit than I deserved. :)

Well, now that's cleared up, let's go back to the interesting part of the discussion.

"The number of planets in the observable universe is finite and unknown. The number of planets in the whole universe is infinite because the universe itself is unbounded and isotropic."

Okay, so I think I understand what you are saying. You are saying that in the whole universe (including the universe beyond the event horizon of the observable universe), we have an actual infinite number of planets. Wow, I've personally never heard that before. I thought that was disproved by the Big Bang..

From my understanding (please correct me if I'm wrong), the universe might be "infinite" in the sense that no matter how far you go, you will never reach the end (sort of like how you would feel if you were travelling along a sphere). But that does not mean that therefore the whole universe has infinite planets.

To me, the conjecture that the whole universe has infinite number of planets seems logically impossible on the following grounds:

1) At the moment of the Big Bang, which happened a finite time ago, there were no planets in the whole universe.2) Between the time of the Big Bang and now, the number of planets in the whole universe went up in discrete numbers.3) Now, we have an actual infinite number of planets in the whole universe

In order for statement #3 to be even possibly true, you must be able to count from 0 to infinity and actually reach it in a finite time, during step #2. And we know that's impossible, therefore given #1 and #2, we cannot have #3.

The only way to escape this conclusion is if you deny #1 or #2.. Is there something wrong with my logic?

I do understand, by the way, the confusion that could come from hearing that the whole universe is isotropic and infinite. But when astronomers say that, they are saying that we might not be able to reach the "edge" of the universe, because space might be bent in around itself. They are not actually saying that the universe has infinite matter and infinite planets. Yeah, it's confusing when these nerdy astronomers speak about infinity. :)

"(sort of like how you would feel if you were travelling along a sphere)."

But it's the opposite of a sphere, so the intuitions about walking along a sphere don't apply. If it was like a sphere then yes it would be finite, just like there are only some many continents that fit on the Earth.

"2) Between the time of the Big Bang and now, the number of planets in the whole universe went up in discrete numbers."

I don't agree that you'd have to count to infinity to reach an infinite number of planets - it's not as if they're being dropped into the universe box one at a time. They're forming everywhere in the universe by the same process.

Space is infinite. The distribution of matter is homogenous within that infinity. It doesn't follow then that matter is infinite?

http://blog.drwile.com/wp-content/uploads/2010/01/univ_map.jpg

IfA) everywhere is infinite and B)everything is an inextricable part of everywhere,

how could everything be a finite, countable number?

Even if we grant that it's a finite number, it's still a much bigger number than 10^22. The odds that we'd have this specific earth-like planet in this specific location may be incredibly small, but the odds that we'd have some earthlike planet somewhere in the universe (and that we'd then be on it) is pretty good.

>> I don't agree that you'd have to count to infinity to reach an infinite number of planets - it's not as if they're being dropped into the universe box one at a time. They're forming everywhere in the universe by the same process.

No, I am not saying they are being dropped into the universe one at a time.. just discrete numbers.

Let me ask you some questions, so that I can get a better grasp on your understanding..

So are you saying that new planets are being created at an infinite # at a time? That would mean that the universe has infinite energy, and that it's constantly creating new matter at an infinite rate? Is that your understanding?

Also, do you believe that the universe existed infinitely (and infinite amount of matter existed eternally) before the Big Bang?

Or maybe you believe that NEW matter is being created continuously at an infinite rate? Maybe that's what you believe (btw, that's called steady state theory), and in that case, all that you said would make sense.

Anyway, even granted that there might be more life-sustaining planets in the universe, like I said, the fine-tuning argument of the universe still stands. In fact, Hitchens (the guy sitting on the left in the video) seems to think that the rarity of Earth-like planets is a point AGAINST the fine-tuning argument! (quite an opposite point that you are making). He's saying that if the universe is so well fine-tuned for life, then we ought to find more life-sustaining planets. So I guess all that is to say that the rarity of Earth is a separate issue from the fine-tuning argument, since the rarity of life-sustaining planets might just be a numbers game that is dependent on how many planets this universe might have. But I believe we only got one universe, and pretty much one Big Bang. So the apparent fine-tuning of the universe stands on a different order of magnitude than the rarity of life-sustaining planets.

Do you believe that big bang means expansion outwards from a central point?

"So are you saying that new planets are being created at an infinite # at a time?"

I'm saying that the amount of matter is proportional to the amount of space. If an infinite amount of space is expanding at a constant rate, then an infinite amount of matter must exist distributed homogenously throughout that infinite space. In any event, the numbers we're talking about are much greater than the one you cited, 10^22.

"Also, do you believe that the universe existed infinitely (and infinite amount of matter existed eternally) before the Big Bang?"

The evidence suggests the universe began to inflate ~13 billion years ago. In that dimension no the universe is not infinite. I can't comment on the amount of matter existing eternally, because who knows what it means to have existed "before" the big bang, the beginning of time as we know it.

"Or maybe you believe that NEW matter is being created continuously at an infinite rate?"

New matter is also being created everywhere always. They're called quantum fluctuations and they generally de-create very quickly!

What do I care what Hitchens has to say? Just because he's atheist, we're supposed to agree??

I can see the point he's making: if a god went out of his way to make this universe capable of life, and then it turned out Earth was the only planet in the whole universe that could support life then that seems very well inefficient. You have an easier time saying the universe was fine-tuned for stars and not for life.

The argument I'm making is that Earth-like planets are not as uncommon as you stated, because the universe is not as small as the observable universe. There's also the problem that the farther away we look the farther back in time we look, so we can't *see* how common Earthlike planets are even in the observable universe past a certain horizon.

Whether any of this suggests "fine tuning" depends on knowledge we don't have, namely whether other universes are possible (which you argue against). So maybe this is the only kind of universe that can exist for reasons physics hasn't uncovered yet.

We know life-supporting planets exist in this universe, so therefore they are possible. Since the universe is homogeneous everywhere, life-supporting planets are possible elsewhere.

"So are you saying that new planets are being created at an infinite # at a time?"

To expand on this, you can't talk about how many planets are being created at a specific time because of the relativity of simultaneity. The universe relative to us will always appear spherical - and thus the universe that we can see will always have a finite volume and a correspondingly finite number of stars. But the observable universe is not the actual universe, which has infinite volume and a correspondingly infinite amount of matter.

If I tell you I have five fish per bowl, and an infinite number of bowls, how many fish do I have?

If there are 10^22 stars per 3×10^80 cubic meters of space, and I have an infinite amount of space, how many stars are there?

For the sake of not going deeper down this really confusing rabbit hole that others might find boring, I want to sort of cut to the chase here. I do enjoy this discussion, and I personally like going back and forth for a long time to fully flesh out all the ramifications of ideas, but l am running into the reality of constrained time on my part, so let me just lay out all my cards here.. I would like to apologize ahead of time for being a bit forward and undiplomatic in this reply..

I would like to just summarize the main contentious points. (btw, I'm assuming that you don't subscribe to the multiverse theory... since it's pseudo-science.. and I'm hoping sincerely that this discussion won't push you in that direction as a "way out".. that would be sad)

Okay, so here goes:

1) You say that: Space is infinite, homogenous and isotropic. This is called Perfect Cosmological Principle. This principle accurately describes what you've been saying.

2) You say that: Matter is distributed homogenously throughout space, and therefore matter is being created continuously as the universe expands into infinity. This model of the universe, which is consistent with your premise of Perfect Cosmological Principle, is called Steady State Theory of the universe. Appropriately, this theory is also called "Infinite Universe Theory", which is exactly what you have been proposing all this time.

My point, put bluntly, is this: The Big Bang theory has disproved the Infinite Universe Theory / Steady State Theory. Check out the wikipedia article or this PBS article on the Steady State Theory. Stephen Hawking himself has said that the discovery of the CMB radiation was the "final nail in the coffin of the steady state theory." In other words, Big Bang theory has disproven this notion of an infinite universe with infinite matter being created. For reason why this would be the case, a simple logical explanation was given in the March 14 comment above, but there are a lot of other scientific evidence that I did not mention which you could read up on. I'm not the one who's saying this. The scientific community at large is saying this. So your argument is against them, not me. I am not saying that therefore you're wrong -- simply that the current evidence seems to disprove the infinite universe model. I have a feeling you might have heard different parts of Steady State theory and Big Bang Theory -- and sort of integrated the two in your mind, but that can't be done, because the those two models are incompatible alternatives to each other.

On a related note, though, don't you think the arguments such as -- "I can explain phenomena X away because there might be objects Y out there in the unobservable universe" -- are, by definition, pseudo-scientific? The argument refers to theoretical planets beyond the event horizon, traveling away faster than the speed of light, so they can never be verified or falsified. So why base our discussions on them? Because if you are allowed to invoke unobservable infinite number of planets, by the same token I can invoke unobservable infinite number of planet Earths where I'm the president of the U.s. And you wouldn't want that ridiculous situation, I know. :)

Apart from all that, though... and this is important.. I just wanted to point out something: Why are we still talking about the rarity of the Planet Earth? Because I've mentioned several times how this is a separate issue from the fine-tuning of the universe. The fine-tuning of the universe is talking about the setup of the universal constants that come way before Earth ever enters the discussion. I just wanted to make sure we are on the same page about that, because I find myself repeating that same point for the 5th time now (counting the 2 times I said it during the talk :)). I'm just worried that I am not making myself clear, because you still seem to be talking as though if you could show that there might be other life-sustaining planets out there, you have solved the fine-tuning problem. Discovering the possibility of another Earth-like planet is not the same thing as discovering how the universe seems to be set up to create planets in the first place. When Hitchens brings up this issue about the rarity of the Earth, Richard Dawkins astutely catches this mistake, and says that "that's a separate question." Yes, it's a separate question.

Sorry for the bluntness of this comment, I just felt that this thread could go on and on talking about infinite and isotropic universe.. But all that talk can only get us, at best, to a conjecture (based on an old Newtonian idea at that) which shows the possibility of other Earth-like planets out there. However, even if we entertain that conjecture, that does not get at the fine-tuning in the constants that govern the universe, which was the main point. The only way you can hope to begin to solve the mystery of the fine-tuning of the constants is if you say, "There are infinite number of universes (and thus infinite sets of different constants) in the unobservable parts of the universe." But if you say that, you would then be going over to the ultimate dark side of pseudo-science -- the infinite multiverse.. which I am guessing you are unwilling to do..

Again, sorry for the barrage, and I hope that you keep an open mind that won't adopt a ridiculous theory (like the multiverse) simply to avoid the eerie implications of what we've been finding. I know you haven't done that, but unfortunately, many people do exactly that. I know this back-and-forth medium is frustrating, so if you would like to have a more face-to-face discussion about this, you can sign up for office hours and we can continue to chat. My wife and I are there at the Y on Thursday afternoons for office hours. (sign up at: www.acts2fellowship.org)

1&2. No I'm not advocating the perfect cosmological principle or steady state theory for the observable universe, which as you cited was disproved by the discovery of the CMB.

It's only in our reference frame, matter was created a long time ago/far away from us. But our reference frame is not the one true reference frame. Simultaneity is relative. We happen to be in a part of spacetime where inflation already happened, galaxies already formed and spring break is over. But to someone 45 billion light years away, we're still in the inflationary epoch.

Re: infinite universe. It's spatially infinite - no matter which way you go, there will always be more of it and it will never repeat.

""I can explain phenomena X away because there might be objects Y out there in the unobservable universe" -- "

What phenomenon am I explaining away?

"The argument refers to theoretical planets beyond the event horizon, traveling away faster than the speed of light, so they can never be verified or falsified."

That's not true, actually. The curvature of the universe can be falsified.

Do you believe we are at the exact center of the universe? You kind of have to if you reject the idea of a universe beyond the observable universe. That's anti-copernican, and doesn't explain why the local geometry is flat.

Then there's the existence of Dark Flow which is direct physical evidence of matter outside the observable universe.

"Because if you are allowed to invoke unobservable infinite number of planets, by the same token I can invoke unobservable infinite number of planet Earths where I'm the president of the U.s."

Not necessarily. But let's grant it anyway. Ok, in another universe, a body shaped like yours became president. What's your argument? It's incredible so it can't be true?

Speaking of pseudoscience, isn't it pseudoscientific to posit a agentic fine-tuner who by unknown mechanisms and for unknown reasons created only the observable universe?

"There are infinite number of universes (and thus infinite sets of different constants) in the unobservable parts of the universe."

I'm not arguing that other universes with different constants would exist in the unobservable part of this universe.

I'll define "this universe" broadly as the region of spacetime that exists post-symmetry breaking the way it did for us. So observable + unobservable.

You have to go up a level to talk about an infinite number of universes starting with the same initial conditions, which would let you be president.

Then it's another level to talk about multiverses forming with different constants. I don't think the former is a requirement for the latter, or vice versa. A good visual representation of this is the video imagining the tenth dimension

I also am just not convinced that it's at all eerie - at least not anymore eerie than knowing that out of 300 million sperm I was the one that made it, or that even though most of this planet is completely inhospitable to my life, I somehow ended up in a part that's quite comfortable. My existence is my cheat sheet - I know I must be possible. The question is how.

Okay, I guess we're talking on different wavelengths here, and we need to agree to disagree. But maybe we actually DO agree completely, it's just that we don't seem to agree because of relativity of simultaneity of reason! :)

Anyway, for the 6th time now.. How does this address the fine-tuning of the constants again? Your example of 300 mill sperms is a classic example of selection bias, which I already covered. The analogy fails, because you don't show that we have 300 mill universes. It seems like you're entertaining that idea, though.. And I admit, if we have infinite universes, you have solved the fine-tuning mystery... it should not be eerie at all, since one of them had to be fine-tuned for life like our universe.

"The analogy fails, because you don't show that we have 300 mill universes."

You're right, I don't show that. It's just more plausible than invoking something that works essentially by magic, which doesn't really explain anything.

I also am not able to show that I competed with 300 million other gametes, but that doesn't mean I should conclude that my father must have built me in his image.

There's a lot of interesting mathematical models of the early inflationary universe which predict a lot of other universes and predict a field where the conditions for inflation are common. One theory is Chaotic Inflation which predicts an eternally inflating fractal cosmology on the largest scales -

I am just amazed by that. Imagine our universe, and the omniverse it lives in, on the largest scales has the same kind of pattern that we can see every day in all living things, trees, circulatory systems, coral...it's so elegant. I don't know about you but I find fractals almost hypnotically beautiful.

It seems like many models of the universe have been brought up here. For anyone interested here is a relatively concise article by William Lane Craig that addresses many of the models proposed. Note that the focus of the article is the cosmological argument(arguing for necessity of a creator if the universe had an absolute beginning), not fine-tuning, and issues with this argument should be discussed in another thread. However the summary and evaluation of universe models is informative.

In looking back on this set of comments, I think we can see a pretty good example of how someone who is trying to avoid the fine-tuning argument could move toward accepting the multiverse theory. In the beginning, Sierra was not willing to go toward the multiverse (and gave it a good attempt to explain the fine-tuning within our one universe), but you can see how at the end, sierra moved toward the multiverse theory -- not because of the overwhelming evidence for it, but because it's personally easier to swallow than the theistic alternative. This has been often the case.

The fine-tuning argument is extremely difficult to answer if you stay within the one-universe theory.. So people opt for the multiverse. If the theistic hypothesis is ridiculous to a person, then of course it's more plausible to choose the multiverse theory simply to avoid the theistic theory. So I'm not saying that that's necessarily disingenuous. That's a legitimate way of choosing between two theories. However, I think it does demonstrate begging the question in a small way.

Please provide a reference for, "For example, if the electromagnetic force constant was different by 1/10^40 (0.000000000000000000000000000000000000001%), then we wouldn’t have any molecules, just elemental atoms floating around..."

There are a lot of articles online for the fine-tuning. Here's one that specifically mentions that figure: http://www.reasons.org/explore/publications/facts-for-faith/facts-for-faith/2001/12/31/anthropic-principle-a-precise-plan-for-humanity

here's another: http://coldcasechristianity.com/2015/the-inexplicable-fine-tuning-of-the-foundational-forces-in-our-universe/ - which quotes Stanford physics professor Leonard Susskind as having said the figure. (He mentions the ratio between electromagnetic force constant and gravity being fine-tuned to 1/10^40)

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